The present invention relates to power management systems and methods that may be advantageously used in managing power consumption in electronic devices, particularly hand operated data input devices. The invention further concerns sensing systems and methods usable as part of a power management system, and for other purposes. More specifically, the invention relates to sensing and power management systems and methods that may be used to conserve battery power in wireless data input devices having components that consume power at a relatively high rate.
Power management in electronic devices is becoming increasingly important as greater reliance is placed on battery power, e.g., for portable computers, personal data assistants (PDAs), tablet computers, cellular phones, pagers, and wireless computer peripherals. The components of such devices are becoming increasingly power hungry, and the demand for longer intervals between battery replacement or recharging has increased. Such devices are often turned on for ready usability but left idle for significant periods of time. This presents an opportunity to reduce depletion of battery power through the use of reduced power modes.
Recently, wireless peripheral devices intended for use with a host computer have been introduced. In particular, cursor control (pointing) devices such as a computer mouse and trackball device have been made wireless by inclusion of a battery power source within the device and the provision of a wireless data link, e.g., an infrared or RF transmitter/receiver pair. Without effective power management, continuous operation of such wireless peripherals will rapidly deplete the limited battery power of the device, thus requiring frequent battery replacement or recharging.
In another line of technological development, cursor control devices utilizing optical surface tracking systems have been introduced and are increasingly being used in lieu of devices relying on conventional opto-electric encoder wheel arrangements. Optical tracking can provide more reliable and accurate tracking by eliminating moving parts (e.g., a ball and associated encoder wheels), which are prone to malfunction from the pick-up of dirt, oils, etc. from the tracked support surface and/or a user""s hand. On the other hand, optical tracking requires considerably more power for driving the circuitry used to illuminate a trackable surface and to receive and process light (image information) reflected from the trackable surface. Exemplary optical tracking systems, and associated signal processing techniques, are disclosed in commonly owned U.S. Pat. No. 6,172,354 (Adan et al.) and applications Ser. No. 09/692,120, filed Oct. 19, 2000, and Ser. No. 09/273,899, filed Mar. 22, 1999, each of which is hereby incorporated by reference in its entirety.
Heretofore, limited use of optical tracking systems has been made in wireless cursor control devices, due to the relatively large power requirements of both the optical tracking system and the wireless data transmitter. In one recent offering, the Logitech Cordless Mouseman(copyright) Optical, multiple sleep and awake modes are utilized to increase battery life. Switching from a full run mode through a succession of reduced power modes is carried out based upon durations of user inactivity. Whenever the user moves the mouse or clicks a mouse button, the mouse returns to the full run mode.
Various types of user proximity detectors are known, and used in power management systems and myriad other applications. For example, Tournai U.S. Pat. No. 5,408,668 discloses a processor based control system for connecting and disconnecting a computer peripheral device (e.g., a display monitor or printer) to a power source. The control is based upon input activity signals received from an input source such as a keyboard, mouse, printer or an occupancy sensor.
Mese et al. U.S. Pat. No. 5,396,443 discloses power saving control arrangements for information processing apparatus. More specifically, the Mese et al. ""443 patent describes various systems for (1) detecting the approach (or contact) of a user associated medium to (or with) the apparatus; (2) placing a controlled object of the apparatus in a non-power saving state when such contact or approach is detected; and (3) placing the controlled object in a power saving state when the presence of the user associated medium (i.e., a stylus pen or part of a user""s body) is not detected for a predetermined period of time.
The ""443 patent describes various types of approach/contact sensors. Among these, various xe2x80x9ctabletxe2x80x9d type sensor systems are described, including electromagnetic, capacitance, and electrostatic coupling tablets. In one embodiment, a contact or approach detecting tablet, and a flat display panel, may be integrally formed with a housing of the information processing apparatus.
Philipp U.S. Pat. No. 5,730,165 describes a capacitive field detector used to provide on-off control of a water fountain or wash basin faucet, based upon a detected approach or presence of a user.
In one embodiment of the Philipp ""165 patent, a voltage-limited current source feeds a charging current to a plate. At the end of a charging interval, a discharge switch controlled by a microprocessor closes briefly to discharge the sensing plate into a charge detector, e.g., a charge detecting capacitor. The amount of charge so transferred is representative of the capacitance of the sensing plate. The charge-discharge process can be repeated numerous times, in which case the charge measurement means aggregates the charge from the plate over several operating cycles. After a predetermined number of cycles of charge and discharge, the charge detector is examined for total final charge, by an A/D converter, and as a result the controller may generate an output control signal on an output line which may be used to cause a faucet to open. After each reading, the controller resets the charge detector to allow it to accumulate a fresh set of charges from the plate. Alternatively, the controller can take a reading after each individual cycle of the discharging switch, and then integrate (or otherwise filter) the readings over a number of cycles prior to making a logical decision resulting in a control output.
Sellers U.S. Pat. No. 5,669,004 discloses a system for reducing power usage in a personal computer. More specifically, a power control circuit is disclosed for powering down portions of a personal computer in response to user inactivity, and for delivering full power to these portions once user activity is detected via one or more sensors. The components to which power is reduced (or removed) are components which can respond almost immediately to being turned on. On the other hand, components which require a period of time to come up to full operation (e.g., disk drive motors, monitor, main processor) are driven to full power. In the primary embodiment that is disclosed, the sensor is a piezoelectric sensor fitted into a keyboard. Sellers discloses that sensors may be positioned at other locations on the computer (a monitor, mouse, trackball, touch pad or touch screen) and that various other kinds of sensors (capacity, stress, temperature, light) could be used instead of piezoelectric sensors.
The present invention has several aspects which may be advantageously (but not necessarily) utilized in combination with each other to provide effective power management in user operated data input devices. Capacitive sensing system and method aspects of the invention are not limited to power management and can be implemented in essentially any application (data input devices or otherwise) where there is a desire to reliably and efficiently sense the presence (or absence) of an object or body portion in contact with or close proximity to another object. Power management aspects of the invention are embodied in user operated data input devices, and methods of power management carried out within such devices. Particularly advantageous use may be made of the capacitive sensing and power management aspects of the invention together with each other, to substantially increase battery life in a wireless cursor control device (e.g., computer mouse or trackball device) or other user operated data input device, especially one including circuit components (e.g., an optical tracking system and RF transmitter) that draw relatively large amounts of electrical power.
In a first aspect, the invention is embodied in a capacitive sensing system for sensing the presence of an object or body portion in contact with or close proximity to another object. A first conductor is capacitively coupled to a ground to thereby form a scoop capacitor having a capacitance which varies in relation to the proximity of the object or body portion to the conductor. A pair of second and third conductors form a bucket capacitor having a capacitance which is larger than a maximum capacitance of the scoop capacitor, and an input threshold switch is provided. Switching means are provided for selectively: connecting at least one of the scoop capacitor and bucket capacitor to a voltage source to charge the at least one capacitor, varying the charge of the bucket capacitor in relation to a relative size of the scoop capacitor, and applying a voltage of the bucket capacitor to the input threshold switch. A detector means is provided for detecting an input state of the input threshold switch. Determining means determine a value (TouchVal) relating to a number of cycles of varying of the bucket capacitor charge corresponding to a detection of a transition of the input threshold switch by the detector means. Signal generating means generate, based upon TouchVal, a signal indicative of an ON state wherein the object or body portion is in contact with or close proximity to another object, and an OFF state wherein the object or body portion is not in contact with or close proximity to another object.
In a second aspect, the invention is embodied in a user operated data input device. First and second data input signal generating means are provided for generating respective first and second data input signals. A power supply is provided for selectively supplying electrical power to the first and second input signal generating means. A sensing system senses the presence of an operation instrumentality in contact with or close proximity to the input device, and generates a signal indicative of an ON state wherein the operation instrumentality is in contact with or close proximity to the input device, and an OFF state wherein the operation instrumentality is not in contact with or close proximity to the input device. A power management system controls the supply of power to the first and second input signal generating means. The power management system provides switching between at least three power states. In a first of the power states, each of the first and second input signal generating means is powered-up to a normal operation level and sampled for input activity. In a second of the power states, each of the first and second input signal generating means are cycled between a powered-up state wherein sampling for input activity is carried out, and a powered down state. In a third of the power states, the first signal generating means remains powered down while the second signal generating means is cycled between a powered-up state wherein sampling for input activity is carried out, and a powered down state. A transition from the first power state to the third power state occurs upon a transition of the sensing system from the ON state to the OFF state. A transition from the third power state to one of the first and second power states occurs upon a transition of the sensing system from the OFF state to the ON state. A transition from the second power state to the first power state occurs upon a detection of input activity during the sampling of the first and second input signal generating means.
In a third aspect, the invention is embodied in a hand-held cursor control device comprising an optical tracking engine including a light source which is flashed. A detector means detects light from the light source which has been reflected off of a surface. Determining means are provided for determining the presence or absence of a trackable surface. A control means controls the light source such that (a) when the determining means determines the presence of a trackable surface the light source is flashed at a first rate permitting tracking of the surface, and (b) when the determining means determines the absence of a trackable surface the light source is flashed at a second rate lower than the first rate.
In a fourth aspect, the invention is embodied in a method for sensing the presence of an object or body portion in contact with or close proximity to another object. The method is carried out with a first conductor capacitively coupled to a ground to thereby form a scoop capacitor having a capacitance which varies in relation to the proximity of the object or body portion to the conductor. A pair of second and third conductors are provided, which form a bucket capacitor having a capacitance which is larger than a maximum capacitance of the scoop capacitor; and an input threshold switch. Switching is performed to selectively: connect at least one of the scoop capacitor and the bucket capacitor to a voltage source to charge the at least one capacitor, varying the charge of the bucket capacitor in relation to a relative size of the scoop capacitor, and apply a voltage of the bucket capacitor to the input threshold switch. An input state of the input threshold switch is detected. A value (TouchVal) is determined, which relates to a number of cycles of varying the bucket capacitor charge corresponding to a detection of a transition of the input threshold switch. Based upon TouchVal, a signal is generated which is indicative of an ON state wherein the object or body portion is in contact with or close proximity to another object, and an OFF state wherein the object or body portion is not in contact with or close proximity to the object.
In a fifth aspect, the invention is embodied in a method of power management carried out by a user operated data input device comprising first and second data input signal generating means for generating respective first and second data input signals, and a power supply for selectively supplying electrical power to the first and second input signal generating means. The method involves sensing the presence of an operation instrumentality in contact with or close proximity to the input device and generating a signal indicative of an ON state wherein an operation instrumentality is in contact with or close proximity to the input device, and an OFF state wherein the operation instrumentality is not in contact with or close proximity to the input device. The supply of power to the first and second input signal generating means is controlled by providing switching between at least three power states. In a first of the power states, each of the first and second input signal generating means is powered-up to a normal operation level and sampled for input activity. In a second of the power states, each of the first and second input signal generating means are cycled between a powered-up state wherein sampling for input activity is carried out, and a powered down state. In a third of the power states, the first signal generating means remains powered down while the second signal generating means is cycled between a powered-up state wherein sampling for input activity is carried out, and a powered down state. A transition from the first power state to the third power state occurs upon a transition of the sensing system from the ON state to the OFF state. A transition from the third power state to one of the first and second power states occurs upon a transition of the sensing system from the OFF state to the ON state. A transition from the second power state to the first power state occurs upon a detection of input activity during the sampling of the first and second input signal generating means.
In a sixth aspect, the invention is embodied in a method carried out by a hand-held cursor control device comprising an optical tracking engine including a light source which is flashed. Light from the light source, which has been reflected off of a surface, is detected. The presence or absence of a trackable surface is determined. The light source is controlled such that (a) when the presence of a trackable surface is determined the light source is flashed at a first rate permitting tracking of the surface, and (b) when the absence of a trackable surface is determined the light source is flashed at a second rate lower than the first rate.
In a seventh aspect, the invention is embodied in an electronic device comprising a housing and a capacitive sensing system contained within the housing. The sensing system senses the presence of an operation instrumentality in contact with or close proximity to the electronic device, and generates a signal indicative of an ON state wherein an operation instrumentality is in contact with or close proximity to the electronic device, and an OFF state wherein the operation instrumentality is not in contact with or close proximity to the electronic device. The capacitive sensing system includes a conductive sensor plate in the form of a flexible label adhesively applied to the housing.